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Abstract:

The present invention relates to a method for detecting leakages in a
system for conducting a medical fluid upstream a shut-off device of the
system as well as systems related thereto. More specifically, the method
is used with systems having a section conducting the medical fluid, the
section being arranged upstream the shut-off device, which is configured
to interrupt or reduce an escaping or outflow of the fluid out of the
section into an area downstream the shut-off device. The system for use
with the present method further has at least one conveying device for
conveying the fluid through the section. The present invention further
relates to a digital storage medium, a computer program product and a
computer program for performing the method for detecting leakages.

Claims:

1-25. (canceled)

26. A method for detecting leakages in a system conducting a medical
fluid, upstream a shut-off device of the system; wherein the system
comprises a section conducting the medical fluid, the section being
arranged upstream the shut-off device; wherein the shut-off device is
configured to interrupt or reduce an outflow or escaping of the fluid out
of the section into an area downstream the shut-off device; wherein the
system further comprises at least one conveying device for conveying the
fluid through the section; wherein the method encompasses the steps of:
interrupting or reducing the fluid flow through the section or out of the
section during a first conveying effort of the conveying device by
setting or adjusting, respectively, the shut-off device for reaching a
first conveying state in the section; reaching a second conveying state
in the section by changing the first conveying effort to a second
conveying effort of the conveying device; emitting at least one signal by
utilization of a signal emitting device into the section of the system
both in the first and the second conveying state; receiving a proportion
of the emitted signal leaving the section by utilization of a signal
receiving device in the first conveying state as a first proportion;
receiving a proportion of the emitted signal leaving the section by
utilization of a signal receiving device in the second conveying state as
a second proportion; and drawing a conclusion whether a leakage is
present by an evaluation of the first proportion in relation to the
second proportion.

28. The method according to claim 25, wherein the emitted signal
comprises radiation, wherein the signal emitting device is a radiation
source for emitting radiation, and wherein the signal receiving device is
a radiation receptor for receiving or detecting radiation.

31. The method according to claim 26, wherein the proportion leaving the
system is reflected, transmitted or scattered radiation.

32. The method according to claim 26, wherein drawing a conclusion
whether a leakage is present by evaluating the first proportion in
relation to the second proportion comprises calculating the difference of
the first and the second proportion and a comparison of the first
proportion, the second proportion and/or the calculated difference to a
threshold value.

33. The method according to claim 26, wherein the first and/or the second
proportion is or reflects a percentage intensity of the emitted signal or
of the emitted radiation.

34. The method according to claim 26, wherein the signal reception device
is further used or applicable or usable or provided or intended for
detecting an optical density or a change thereof.

35. The method according to claim 26, wherein the fluid flow of the
medical fluid is stopped by utilization of the shut-off device in the
first conveying state.

36. The method according to claim 26, wherein the conveying device is
stopped in the second conveying state.

37. The method according to claim 26, wherein a centrifugal pump is used
as the conveying device.

38. The method according to claim 26, wherein an alarm is issued in case
a leakage is detected.

39. A system comprising a treatment cassette, comprising at least one
section conducting a medical fluid, a conveying device for conveying the
fluid through the section, a shut-off device for interrupting or reducing
the fluid flow through the section, a signal emitting device for emitting
a signal, a signal receiving device for receiving a proportion of the
emitted signal, and a controller configured to execute a method according
to claim 26.

40. The system according to claim 39, wherein the signal emitting device
is a radiation source for emitting radiation, and wherein the signal
receiving device is a signal receptor for receiving a proportion of the
emitted radiation.

41. The system according to claim 39, further comprising a comparing
device for comparing the first proportion of the emitted signal received
in the first conveying state and the second proportion of the emitted
signal received in the second conveying state.

42. The system according to claim 39, further comprising a decision
device for drawing a conclusion whether a leakage is present by
evaluating the first proportion in relation to the second proportion.

43. The system according to claim 39, wherein at least the conveying
device is part of the treatment cassette.

44. The system according to claim 39, wherein the signal emitting device
is configured as a radiation source for emitting electromagnetic
radiation.

45. The system according to claim 39, wherein the signal receiving device
is configured to detect reflected and/or transmitted and/or scattered
radiation.

46. The system according to claim 39, further comprising an alarming
device configured to issuing an alarm when a leakage is detected.

47. A medical-technical treatment device, configured to execute the
method according to claim 26.

48. A non-transitory computer-readable storage medium with an executable
program stored thereon, wherein the program instructs a programmable
computer system to execute the steps of the method according to claim 26.

[0002] The present invention relates to methods for detecting leakages in
systems conducting a medical fluid, systems for detecting leakages,
including medical-technical treatment apparatuses. The present invention
also relates to digital storage media, computer program products, and
computer programs for detecting such leakages.

BACKGROUND OF INVENTION

[0003] The occurrence of leakages in systems which conduct medical fluids
may regularly be problematic or even dangerous. Early detection of such
leakages is thus of great importance.

[0004] One object of the present invention is to propose a method suited
for the detection of leakages. Furthermore, an appropriate system as well
as a medical-technical treatment apparatus are to be provided.

[0005] All advantages achievable by means of the method according to the
present invention may undiminishedly also be achieved by means of the
system and/or the medical-technical treatment apparatus.

[0006] The method according to the present invention is suited and
provided for the detection of leakages in a system conducting a medical
fluid, in particular upstream a shut-off device of the system, the system
comprising at least the following components: at least one conveying
device, a shut-off device and a section conducting the medical fluid, the
section being arranged upstream the shut-off device. The conveying device
serves for conveying the fluid through the section of the system. This is
feasible at least in the direction towards the shut-off device.
Furthermore, the conveying device may optionally be designed or embodied,
respectively, or arranged or configured in addition for conveying in the
opposite direction.

[0007] The method according to the present invention encompasses
interrupting or reducing a fluid flow of the medical fluid through or out
of the section during a first conveying effort of the conveying device.
In order to interrupt or reduce, the shut-off device is adjusted or set,
respectively, accordingly, e.g., closed. In this adjustment setting, a
first conveying state is reached.

[0008] Further, the method according to the present invention encompasses
reaching a second conveying state in the section by changing the
conveying effort of the conveying device; the first conveying effort
turns into a second conveying effort.

[0009] In a further step, the method according to the present invention
encompasses emitting at least one signal by means of a signal emitting
device--both in the first and the second conveying state--into the
section of the system (measurable, e.g., within the section by means of a
sensor present therein) and, where appropriate, through the section
(measurable, e.g., as a transmittance on the side of the section opposite
to the signal incidence side, or as a reflexion on the side of the
section from which the signal was emitted).

[0010] The proportion of the emitted signal leaving the section again in
the first conveying state (or penetrating into the section and being
received within the section by the signal reception device) is thereby
received by means of a signal reception device, the said proportion in
the following being referred to as first proportion. Analogously, the
proportion of the emitted signal leaving the section again in the second
conveying state (or penetrating into the section and being received
within the section by the signal reception device) is thereby received by
means of the signal reception device, the said proportion in the
following being referred to as second proportion.

[0011] Subsequently, in a further step of the method according to the
present invention, based on an evaluation of the first proportion in
relation to the second proportion, a conclusion may be drawn whether or
not a leakage is present or has occurred, respectively.

[0012] The system according to the present invention comprises at least
one controller suited and/or configured and/or provided for executing the
method according to the present invention.

[0013] The medical-technical or medical treatment apparatus according to
the present invention is provided for being connected, or is connected,
with at least one system according to the present invention. In addition
or instead, the treatment apparatus according to the present invention
is, in certain embodiments, provided or intended for executing at least
one method according to the present invention.

[0014] Embodiments according to the present invention may comprise some or
all of the following features in any arbitrary combination.

[0015] In some embodiments according to the present invention, the emitted
signal encompasses or consists of ultrasonic waves. In such a case, the
signal emitting device emits ultrasonic waves and the signal receiving
device detects the ultrasonic waves. The system according to the present
invention may be designed or embodied correspondingly.

[0016] In certain embodiments according to the present invention, the
signal emitting device and/or the signal receiving device are or comprise
piezoelectric crystals.

[0017] In some embodiments according to the present invention, the emitted
signal encompasses or consists of radiation. In such a case, the signal
emitting device is a radiation source for emitting radiation and the
signal receiving device is a radiation receptor for receiving or
detecting radiation. The system according to the present invention may be
designed or embodied accordingly.

[0018] In certain embodiments according to the present invention, the
signal emitting device and the signal receiving device are one and the
same device. Such a device thus serves both for emitting and receiving
the respective signal. Such an embodiment or construction according to
the present invention may be realized regardless of the type of signal to
be transmitted and received. A common or combined embodiment or
construction of a signal emitting device and signal receiving device in
one single device being able to vary after switching or reversing the
operating principle between emitting and receiving is--like an embodiment
or construction of signal emitting device and signal receiving device as
separate devices but present in one common housing--both when using
ultrasound and when using other types of signals subject-matter of
embodiments according to the present invention.

[0019] The present invention may, without, however, being limited hereto,
advantageously be used for detecting leakages in an extracorporeal blood
circuit and/or leaking connectors in or at a blood treatment apparatus
such as, e.g., a dialyzer.

[0020] The term "system" as used herein in certain embodiments of the
present invention refers to a (medical-)technical system--as opposed to a
vascular system of a patient.

[0021] In certain embodiments of the present invention, the system
comprises an arrangement of several components such as lines, tubes,
channels, flow-promoting and/or flow-reducing elements, supply devices
and/or drain devices, and the like, the arrangement being suited and/or
provided or intended for conducting fluids. In certain embodiments, the
system is designed or embodied, for instance, as a tube system such as an
extracorporeal blood circuit without, however, being limited hereto.

[0022] The system is designed or embodied and/or provided or intended for
receiving and/or conducting at least one medical fluid by means of a
section contained in the system, such as an interior, e.g., a line
interior, of the system.

[0023] The term "medical fluid" as used herein in certain embodiments
according to the present invention refers to a fluid which is present or
flowing extracorporeally and--e.g., during an extracorporeal blood
treatment--is preferably to be treated.

[0024] The medical fluid in some embodiments according to the present
invention is a liquid such as blood, dialysate, substituate, drug
solutions, a gas, or a combination or mixture thereof.

[0025] The term "section" as used herein in certain embodiments according
to the present invention refers to a part or portion or segment or
section, respectively, of the system in which the leakage to be detected
occurs or is to be ruled out.

[0026] The term "leakage" as used herein refers to a leak,
an--unwanted--opening, a leakiness or a hole within the fluid-conducting
system, in particular of the section through which the fluid conducted
within the system may unwantedly escape from the system's interior to an
exterior of the system. The occurrence of leakages may have arbitrary
causes; these causes as such are irrelevant as regards the present
invention.

[0027] The term "shut-off device" as used herein refers to a device or
means, respectively, arranged at or on, respectively, or in the system,
the device or means, respectively, being suited and/or provided or
intended for reducing or interrupting or preventing, respectively, a
streaming or a flow of the medical fluid through at least one section of
the system.

[0028] In certain embodiments of the present invention, the shut-off
device is intended or provided for interrupting or reducing an escaping
or flowing of the fluid from or out of the section into an area
downstream the shut-off device.

[0029] The term "downstream" in certain embodiments according to the
present invention is to be understood as a streaming direction within the
section, which when executing the method as described herein leads away
from the conveying device.

[0030] The shut-off device may, without being limited hereto, be a clamp,
such as an arterial clamp or a venous clamp of an extracorporeal blood
circuit, an inductor or choke, respectively, a valve, a shut-off valve,
and the like, or may comprise one or more such elements. It may be one
piece or comprise several parts. The shut-off or barrier effect of the
shut-off device may be a result of the interaction of several, i.e.,
multiple, shut-off components, or, however, solely of one single shut-off
component.

[0031] The term "conveying device" as used herein in certain embodiments
according to the present invention refers to a device or means,
respectively, suited and/or provided or intended for conveying the
medical fluid within an interior of the system or a section thereof,
respectively, or through or along the interior or the section. Conveying
the medical fluid may be effected indirectly or directly.

[0032] The concrete design or arrangement or construction, respectively,
of the conveying device is not limited according to the present
invention. Non-limiting examples include non-occluding pumps such as a
centrifugal pump, and the like.

[0033] The term "conveying effort" as used herein in certain embodiments
of the present invention, in certain embodiments according to the present
invention relates to an output or effort or performance, respectively, or
work performed by the conveying device for conveying the medical fluid.
This may be measured by means of, e.g., a voltage metering or a current
measurement at the inlet of the conveying device.

[0034] In some embodiments according to the present invention, the
conveying effort corresponds to a conveying output or performance,
respectively, (e.g., in milliliters per minute, ml/min) which would be
conveyed within the section by means of the conveying device in case the
shut-off device being open.

[0035] In some embodiments according to the present invention, the
conveying effort corresponds to a characteristic of the conveying device
variable during the use of the conveying device. This includes a set or
targeted or intended or conducted number of revolutions per minute of the
conveying device.

[0036] A conveying effort in certain embodiments of the present invention
refers to a state of the conveying device during conveying the medical
fluid, in particular a state for which the conveying device was adjusted
for conveying the medical fluid, e.g., by setting or specifying,
respectively, certain parameters such as a conveying pressure, a
conveying output or performance, a conveying speed, and the like.

[0037] "Changing a conveying effort", e.g., changing the first conveying
effort to become a second conveying effort, may be achieved by changing
at least one of the parameters set or adjusted, respectively, or settable
or adjustable, respectively, for a conveying state, such as, for example,
by changing the rotational speed.

[0038] Thereby, the--first and/or second--conveying effort performed by
the conveying device may be constant or not constant. Preferably, the
first and/or second conveying effort performed by the conveying device is
substantially or completely constant.

[0039] The terms first and second "conveying state" in certain embodiments
according to the present invention describe the state appearing in
relation to a first and second flow rate downstream the shut-off device
appearing in the section as a result of both the conveying effort of the
conveying device and the barrier effect of the shut-off device.

[0040] The first conveying state and the second conveying state may be the
same or different. At least one of the two conveying states may be zero.

[0041] Thus, a first conveying state may be zero, expressed, e.g., by a
flow of 0 ml/min, measured or at least measurable downstream the shut-off
device. This may be a result of a complete shut-off of a flow across the
shut-off device. Likewise, a second conveying state may be zero which
may, e.g., be a result of a complete stop of the conveying device.
However, the present invention is not limited to measurements or
examinations or analyses, respectively, during complete shut-off by means
of the shut-off device or complete interruption of the fluid flow by
stopping the conveying device, or feasible only in this way, as is
recognizable for the skilled person. Rather, it is also possible to
achieve the advantages of the method according to the present invention
with the shut-off device being only partly shut or closed, respectively,
and accordingly only partial throttling of the conveying device. These
embodiments are encompassed by the present invention as well. This is
expressed by the use of the term "conveying state" as described above.

[0042] In certain embodiments, the present invention encompasses that
initially a first conveying state is considered, and subsequently the
second conveying state. However, the present invention is not limited
hereto. For instance, the order of the examination or measurement is
arbitrary as can also be taken from FIGS. 2 to 5. For example, in some
embodiments initially the conveying device may be stopped or throttled
and only after that the shut-off device may be shut off or throttled, or
vice versa.

[0043] In certain embodiments of the present invention, the emitted
radiation--wherein radiation here is to be understood as an example for a
signal as used herein--is or encompasses electromagnetic radiation such
as visible light.

[0044] In certain embodiments of the present invention, the emitted
radiation is or encompasses infrared radiation, e.g., from a narrowband
infrared light source. A peak wavelength of the infrared radiation is
preferably approximately or exactly 805 nm.

[0045] The term "radiation receptor" as used herein in certain embodiments
of the present invention refers to a device or a means or a sensor,
respectively, which is suited and/or provided or intended and/or designed
or embodied for receiving and/or detecting the radiation emitted out of
the section of the system.

[0046] Non-limiting examples of radiation receptors include optical
detectors such as a photodiode, a photoconductive cell or a photo
transistor, and the like.

[0047] The radiation receptor may, like the radiation source, be designed
or embodied in one piece or consisting of or comprising several parts
and/or may be designed or embodied by means of one or more component(s)
for receiving and/or emitting radiation. In some embodiments of the
present invention, the radiation receptor is provided or intended and
designed or embodied as an individual and/or independent component. In
some embodiments of the present invention, the radiation receptor is
provided in one shared or common physical arrangement such as a shared or
common housing together with the radiation source.

[0048] The term "signal receiving device" as used herein goes beyond the
term "radiation receptor" as described above as regards content. A signal
receiving device may be a radiation receptor; however, it is not limited
to receiving radiation. Instead of--or in addition to--radiation, another
signal, e.g., an ultrasonic signal, may be received. The same relation
applies to the terms "radiation source" and "signal emitting device".

[0049] The term "receiving" a proportion of the emitted signal, e.g., of
the emitted radiation as used herein in certain embodiments of the
present invention refers to a targeted reception or detection of the
signal emitted out of the section of the system, e.g., the emitted
radiation.

[0050] The "proportion of the emitted signal" may be a proportion of a
signal, e.g., radiation, which leaves the section--e.g., by reflexion,
transmittance, scattering etc.--or a proportion of a signal, e.g.,
radiation, which has penetrated the section and was measured therein.

[0051] The term "proportion" as used herein in certain embodiments of the
present invention refers to a part or portion, respectively, e.g., a
fractional part or subset, to which the received signal, e.g., the
received radiation, amounts in relation to the originally emitted signal.

[0052] The proportion of the emitted signal, e.g., radiation, which is
received again after emission, in some embodiments according to the
present invention is a fractional part of an intensity (measured, e.g.,
as amplitude of a signal, as counts, as counts per time unit, as electric
potential after corresponding conversion, electric current, frequency,
etc.).

[0053] Counts may thereby, without being limited hereto, be obtained as
follows: When using a signal receiving device which is designed or
embodied as a photo receiver which operates as a
light-to-frequency-converter, the sensor used delivers a frequency
proportional to the received light intensity. For the evaluation, e.g.,
the edges of the signal are counted over a certain time unit; each edge
is thereby classified as a count.

[0054] In some embodiments of the present invention, this proportion of
the emitted signal or of the emitted radiation leaving the system or the
section of the system, respectively, is exclusively or also a reflected
signal. In some embodiments of the present invention, the proportion of
the emitted signal or of the emitted radiation leaving the system or the
section of the system, respectively, is exclusively or also a transmitted
signal. In certain embodiments of the present invention, the proportion
of the emitted signal, e.g., of the emitted radiation, leaving the system
or the section of the system, respectively, is an exclusively or also
scattered, e.g., sidewards or laterally scattered, signal, e.g.,
radiation.

[0055] For drawing a conclusion whether a leakage is present, by means of
an evaluation of the first proportion in relation to the second
proportion, in certain embodiments according to the present invention a
comparison of the first proportion and the second proportion, or of the
amounts or levels or extents or the characteristics, respectively, is
intended or provided.

[0056] The comparison of the first proportion and the second proportion in
certain embodiments of the present invention is made by comparing a first
average value of a first received signal received as a first proportion
over a certain first time period to a second average value of a second
received signal received as a second proportion over a certain second
time period.

[0057] In some embodiments of the present invention, the comparison is
made by subtracting the first proportion or the average value of the
first proportion from the second proportion or the average value of the
second proportion in order to obtain a difference or a difference value.

[0058] In some embodiments, the comparison is made by comparing signal
spectra or radiation spectra of the first and the second proportion of
the received signal or of the received radiation. For example, the
absolute values of signal maxima or radiation maxima and/or signal minima
or radiation minima of the recorded signal spectra or radiation spectra
may be compared.

[0059] In some embodiments of the present invention, the comparison is
made by establishing a relation between the first proportion or the first
average value thereof and the second proportion or the second average
value thereof.

[0060] In certain embodiments of the present invention, drawing a
conclusion whether a leakage is present encompasses or consists of a
comparison with a threshold value. Thereby, a difference, a relation or a
value derived in any other way may be compared with the threshold value.
The difference or the relation may in particular be determined as
described above.

[0061] The threshold value may in particular be a predetermined threshold
value or reference value such as, for example, a threshold value
detected, calculated, estimated, or the like, in a system or a section,
respectively, without leakage.

[0062] In certain embodiments of the present invention, the first and/or
the second proportion is or reflects a percentage signal intensity or
radiation intensity (I).

[0063] In certain embodiments of the present invention, the signal
reception device, in particular when being designed or embodied as
radiation receptor, is used for detecting an optical density or a change
hereof. The latter may serve for detecting a leakage but is, however, not
mandatorily necessary.

[0064] In such embodiments, it may, for example, advantageously be
possible to differentiate between the presence of blood or water in an
extracorporeal blood circuit.

[0065] In order to execute the method according to the present invention,
in certain embodiments according to the present invention a fluid flow of
the medical fluid through the section of the system in the first
conveying state is stopped by means of the shut-off device. The flow may
be stopped, i.e., be set to zero. In other embodiments according to the
present invention, the fluid flow is only appropriately reduced or
throttled by means of the shut-off device, however, not completely
stopped.

[0066] In such a case, the conveying device may or may not continue
conveying.

[0067] In certain embodiments of the method according to the present
invention, it is intended to stop the conveying device in the second
conveying state. In other embodiments according to the present invention,
the conveying device is only throttled, however, not completely stopped.

[0068] In certain embodiments of the present invention, it is intended to
issue an alarm if executing the method according to the present invention
would lead to the result or the assumption that a leakage is present in
the fluid-conducting system. Depending on the wish or request and/or the
demand or requirement, respectively, the alarm may be an optical alarm,
an acoustic alarm or any arbitrarily suited alarm as well as a
combination of different alarms.

[0069] All, a few or some steps of a method according to the present
invention as described exemplarily and in a non-limiting way with regard
to the appended drawing may be performed automatically. For each of the
procedural steps as described in relation to the method according to the
present invention, the apparatuses according to the present invention may
comprise corresponding devices for the implementation thereof.

[0070] In certain embodiments of the present invention, the system
according to the present invention comprises at least one treatment
cassette comprising at least one section conducting a medical fluid, a
conveying device for conveying the fluid through the section as well as a
shut-off device for interrupting or reducing the fluid flow through the
section.

[0071] The term "treatment cassette" as used herein refers to a functional
device that is intended or provided and/or is or will be used for
performing a medical treatment, e.g., an extracorporeal blood treatment.

[0072] Examples of treatment cassettes include a blood cassette, e.g., in
form of a cast part or an injection-molded part, irrespective of whether
or not the blood cassette is designed or embodied as a one-way article or
a disposable.

[0073] In certain embodiments of the system according to the present
invention, at least the conveying device is part of the treatment
cassette.

[0074] The system according to the present invention in certain
embodiments comprises a radiation source for emitting radiation as a
signal emitting device.

[0075] The radiation source in certain embodiments is designed or embodied
for emitting electromagnetic radiation, in particular infrared light.

[0076] The signal emitting device in some embodiments is embodied or
designed for emitting ultrasonic waves.

[0077] In certain embodiments according to the present invention, the
system comprises a signal receiving device configured and/or provided or
intended for receiving a proportion of the emitted signal and a
controller for executing the method according to the present invention.

[0079] In certain embodiments according to the present invention, the
signal receiving device is designed or embodied as a device for receiving
ultrasonic waves.

[0080] In some embodiments according to the present invention, the signal
receiving device is designed or embodied as a device for receiving
radiation.

[0081] The system according to the present invention in certain
embodiments further comprises at least one comparing device for comparing
the first proportion received in the first conveying state to the second
proportion of the emitted signal, e.g., of the emitted radiation and/or
of the ultrasonic waves, received in the second conveying state.

[0082] In certain embodiments of the system according to the present
invention, further a decision device configured and/or provided or
intended for drawing a conclusion whether a leakage is present in or
within, respectively, or at or on, respectively, the system by means of
an evaluation of the first proportion in relation to the second
proportion.

[0083] In certain embodiments, the system further comprises at least one
alarming device configured for issuing an alarm when a leakage is
detected.

[0084] In some embodiments according to the present invention no gas-pump
and/or no flow-meter for measuring the gas flow are used or provided,
and/or no gas flow is measured.

[0085] In certain embodiments according to the present invention no
negative pressure is applied during the execution of the method according
to the present invention. Accordingly, in some embodiments according to
the present invention no devices for applying negative pressure are
provided and/or are used during the execution of method according to the
present invention.

[0086] In some embodiments according to the present invention no result in
absolute numbers is received or established.

[0087] In certain embodiments according to the present invention no
flowrate is measured or determined.

[0088] The object according to the present invention is further also
solved by a digital storage medium, a computer program product and a
computer program.

[0089] A digital storage medium, in particular in the form of a disk, CD
or DVD, having electrically readable control signals, may interact with a
programmable computer system such that the execution of the technical
steps of a method according to the present invention is prompted.

[0090] Thereby, all, a few or some of the technically executed steps of
the method according to the present invention may be prompted.

[0091] A computer program product comprises a program code stored on a
machine-readable medium for prompting the execution of the technical
steps of the method according to the present invention when executing the
computer program product on a computer.

[0092] The term "machine-readable medium" as used herein in certain
embodiments of the present invention refers to a medium containing data
or information which is interpretable by software and/or hardware. The
medium may be a data medium such as a disk, a CD, DVD, a USB flash-drive,
a flashcard, an SD card, and the like.

[0093] A computer program comprises a program code for prompting the
execution of the technical steps of a method according to the present
invention when executing the computer program on a computer.

[0094] It applies also to the computer program product and the computer
program that all, a few or some of the technically performed steps of the
method according to the present invention are prompted.

[0095] Certain embodiments according to the present invention comprise one
or more of the following advantages.

[0096] The present invention provides a method and apparatuses by means of
which in some embodiments according to the present invention the
detection of leakages--irrespective of which cause--in fluid-conducting
systems is advantageously and in a simple manner possible.

[0097] As the intensity of the detected signal, e.g., of the detected
radiation, of the flowing blood differs from that of non-flowing or
still-standing blood, it may, in certain embodiments of the present
invention, for example, in an advantageously simple manner be possible to
observe or optically detect, respectively, a change in the distribution
of blood cells within the section of the system, and, due to the change,
easily deduce a leakage in the blood-conducting system.

[0098] Pressure-holding or maintenance tests which are usually established
for checking the leak tightness of fluid-conducting systems comprising
occluding pumps such as roller pumps, hose pumps, displacement pumps
etc., are, due to the underlying principle, not feasible for detecting
leakages with constant pressure sources, i.e., non-occluding pumps such
as centrifugal pumps, as the pressure will be constant also with small
leakages being present. For such systems with non-occluding pumps, the
present invention advantageously offers a simple and little elaborate
possibility of detecting leakages nevertheless.

[0099] The use of an optical sensor may hereby in particular be of
advantage for achieving greater accuracy also in case of small leakages,
which is not possible by, e.g., flow sensors.

[0100] Additionally, the optical sensor used according to the present
invention is an advantageously simple sensor which may at the same time
contribute to reducing the constructional and/or financial effort
associated with the system.

[0101] Furthermore, in certain embodiments of the present invention it may
advantageously be possible to conduct further measurements such as, for
example, a differentiation between blood and water and/or air or
measurements of hematocrit hemoglobin concentrations, respectively, and
the like while using one and the same sensor which may also be used for
executing the method according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0102] In the following, the present invention is described merely
exemplarily with regard to the appended figures. In the drawing, same
reference numerals refer to same or identical elements. It applies:

[0103] FIG. 1 schematically shows a section of a system according to the
present invention;

[0104] FIG. 2 shows the course of an optical signal in a test set-up
without leakage;

[0105] FIG. 3 shows the course of an optical signal in case of a leakage
generated by means of a 0.4×19 mm-cannula;

[0106] FIG. 4 shows the course of an optical signal in case of a further
leakage generated by means of a 0.6×25 mm-cannula; and

[0107] FIG. 5 shows the course of an optical signal in case of a still
further leakage generated by means of a 0.6×25 mm-cannula, during a
transmittance measurement.

DETAILED DESCRIPTION

[0108] For clarification of the method according to the present invention,
the time intervals of the measurements in the following exemplary
embodiments were chosen to be very long in order to obtain a presentation
as illustrative and clear as possible for the purpose of describing the
present invention. The duration for executing the method according to the
present invention may, of course, be (considerably) shorter.

[0109] The following examples are furthermore explained by means of
radiation as a signal. It is recognizable for the skilled person that the
present invention is not limited to the use of radiation as a signal.
Instead of radiation, rather also another type of signal may be used, as
described above.

[0110] FIG. 1 schematically shows a section of a system 1000 according to
the present invention.

[0111] As shown in FIG. 1, the system 1000 is embodied as an
extracorporeal blood circuit. The system 1000 may comprise or be a (e.g.,
plastic) tubing set.

[0112] The system comprises an arterial blood line 1 and a venous blood
line 3 comprising a venous chamber 31.

[0113] For conveying blood in an interior of a line of the extracorporeal
blood circuit, a conveying device 5, e.g., in form of a centrifugal pump
or any other design or construction, which, e.g., is overflowable or
non-occluding, is provided.

[0114] The venous leg of the extracorporeal blood circuit comprises a drip
chamber 2. The drip chamber 2 comprises a conventional ventilation
device, which is not shown. The ventilation device in some embodiments
according to the present invention is an air extraction valve. In certain
embodiments according to the present invention, the ventilation device
comprises a membrane, preferably a hydrophobic membrane.

[0115] In FIG. 1, the direction of the extracorporeal flow of the blood
within the line interior of the extracorporeal blood circuit during a
blood treatment is indicated by means of the filled arrowheads.

[0116] The system 1000 comprises a venous clamp which in the frame of the
embodiment according to the present invention of FIG. 1 exemplarily
serves as a shut-off device 7.

[0117] The system 1000 further comprises an arterial clamp 9. The arterial
clamp 9 may, but does not have to, be used additionally or alternatively
to the shut-off device 7, as a shut-off device in the frame of the
present invention.

[0118] For the extracorporeal blood treatment, a blood treatment device 11
is arranged in or within or is in fluid contact with, respectively, the
extracorporeal blood circuit.

[0119] In the example of FIG. 1, the blood treatment device 11 is
connected with the drip chamber 2 by means of a venous line section 4.
Further, it is connected with the conveying device 5 by means of an
arterial line section 6.

[0120] Examples for the blood treatment device 11 encompass a blood filter
for cleaning a patient's blood during a hemodialysis treatment and/or a
hemofiltration treatment, and the like, but are not limited hereto. The
blood treatment device 11 may be designed as a one-way product or a
disposable device.

[0121] The blood treatment device 11 further is in fluid contact with a
dialysate circuit 13.

[0122] The dialysate circuit 13 comprises a dialysate inlet 131 and a
dialysate outlet 133 or is connected with devices suited and/or provided
for supplying or discharging, respectively, dialysate, respectively. The
dialysate circuit 13 comprises a conventional dialysate pump not shown in
FIG. 1 for conveying dialysate within the dialysate circuit 13.

[0123] In the supply line 135 leading from the dialysate inlet 131 to the
blood treatment device 11, a first valve V1 is arranged in or within the
dialysate circuit 13.

[0124] In the drain line 137 leading from the blood treatment device 11 to
the dialysate outlet 133, a second valve V2 is arranged.

[0125] The supply line 135 and the drain line 137 of the dialysate circuit
13 are in fluid communication via a connection line 139 which optionally
comprises a bypass valve V3.

[0126] As shown in FIG. 1, a radiation receptor 15 is arranged within the
arterial blood line 1 of the extracorporeal blood circuit.

[0127] The radiation receptor 15 may be an optical detector. The radiation
receptor 15 may, e.g., be provided and/or designed and/or configured
and/or intended for detecting changes in the light intensity of emitted
and received radiation, caused by the presence and possibly the motion of
the red blood cells of the blood flowing extracorporeally.

[0128] The radiation receptor 15 may, as shown here in FIG. 1, be designed
integrally, i.e., in one shared or common body with a radiation source
17, e.g., a infrared source.

[0129] In other embodiments, not shown here, radiation receptor 15 and
radiation source 17 may, however, also be designed physically separated
from each other and/or arranged spatially separated from each other.

[0130] For detecting a potential leakage in the section 100 of the system
1000, in an exemplary embodiment of the method according to the present
invention initially the shut-off device 7 and the valves V1 and V2 in the
dialysate circuit 13 are closed.

[0131] In certain embodiments of the method according to the present
invention, this may be carried out without changing a yet present,
constant rotational speed of the conveying device 5 or without setting
another constant rotational speed than one of those constant rotational
speeds which are used during a patient's treatment anyway or regularly.
In other embodiments, the rotational speed of the conveying device 5,
however, may definitely change or be changed in order to perform the
method as described herein.

[0132] Valve V3--if present--is opened subsequently.

[0133] This way, a static pressure difference is built up across the
conveying device 5.

[0134] During the first conveying state reached or set herewith which in
absence of a leak/a leakage downstream the conveying device 5 is or may
be 0 ml/min (in words: zero), the radiation receptor 15 receives that
proportion of the emitted radiation which is reflected by the blood. This
proportion is to be understood as the first proportion.

[0135] In order to record a further proportion, denoted as second
proportion, of the light emitted by the radiation source 17 in a second
conveying state of the conveying device 5 for reference, the conveying
device 5 is stopped for a certain amount of time. The second conveying
state therefore reliably corresponds to a flow standstill of the blood
within the considered section of the extracorporeal blood circuit.

[0136] The signal recorded during a flow standstill (second proportion) of
the second conveying state is compared to the signal related to or
obtained from the rotating conveying device 5 (first proportion) of the
first conveying state.

[0137] After an undetermined or predetermined, in any case sufficient,
amount of time, the conveying device 5 is restarted.

[0138] In case the first proportion differs from the second proportion,
e.g., when considering their average values, of the unchangedly emitted
optical signal, i.e., between the continuously rotating conveying device
5 and the stillstanding conveying device 5, the presence of a blood leak
within the extracorporeal blood circuit, e.g., a leakage in one of the
two patient lines 1, 3 of a tubing set and/or a leakage in a connection
to the blood treatment device 11 may be inferred or assumed. A
corresponding alarm signal may be issued.

[0139] If no change in the signal or in its average value or another
mathematical evaluation thereof is detected, the leakage test is passed.

[0140] Also possible and contemplated according to the present invention
is the following approach: With valve V2 being closed, a liquid, e.g.,
dialysate, is conveyed across the membrane of the blood treatment device
11 to the blood side by means of the dialysate pump (not shown) or
another accordingly switched pump. There, the liquid transported to the
blood side disperses to both the venous line section 4 and the arterial
line section 6. Across or over each the drip chamber 2 and the, in
particular during standstill, overflowable conveying device 5, also the
arterial blood line 1 and the venous blood line 3 may be rinsed. This
way, the whole system 1000 may be filled with liquid. The arterial blood
line 1 and the venous blood line 3 may thereby directly or via an
adapter, or the like, be short-circuited or connected to each other.
Alternatively, the arterial blood line 1 and the venous blood line 3 are
not connected with each other. The liquid flowing through the lines may
be discarded. Subsequent to the approach described herein, the conveying
device 5 may be operated in order to remove air possibly present in the
system 1000 from the system 1000 by means of the drip chamber 2 or its
ventilation device.

[0141] In the following FIGS. 2 to 4, in each case the course of the
optical signal of the reflected radiation is represented as a number
proportional to the light intensity over the time t, respectively. In
FIG. 5, instead, the course of the optical signal of the transmitted
radiation is represented measured as a number proportional to the light
intensity over the time t (e.g., in seconds or another unit).

[0142] For easier understanding, in the following experiment descriptions
of FIGS. 2 to 5, the reference numerals of the components shown in the
section 100 of the system 1000 according to the present invention are
used each, even though these components are partly not shown in the
figures described in the following.

[0143] FIG. 2 shows the course of the optical signal in a test set-up
without leakage.

[0144] In this test set-up, which has led to the result of FIG. 2, the
conveying device 5 was initially operated with a continuous rotational
speed of 4500 rpm. The tubing set did not have a leakage.

[0145] The shut-off device 7 was initially open (area 19). Without
changing the rotational speed of the conveying device 5, the shut-off
device 7 was closed after a little bit more than 50 time units (area 21;
corresponds to the first conveying state). In FIG. 2, the average value
of the first proportion of the received radiation is easily recognizable
at about 880 units of measurement or dimensional units.

[0146] Subsequently, the conveying device 5 was stopped (area 23;
corresponds to the second conveying state) and a little bit later on,
e.g., after 25 time units as shown in FIG. 2, restarted (area 25). The
average value of the second proportion of the received radiation is also
at about 880 units of measurement or dimensional units.

[0147] A difference between the two average values (first proportion and
second proportion) thus results in about ±0 measurement or dimensional
units.

[0148] A comparison of the difference and a threshold value (not indicated
here) would thus--due to lack of a difference--lead to the result that a
leakage is not detectable.

[0149] Towards the end of the experiment, the shut-off device 7 is
re-opened (area 27).

[0150] The experiment as described by means of the course of the curve of
FIG. 2 was repeated with specifically placed leakages within the tubing
set: In the implementations of the tests shown in FIGS. 3 to 5, an open
syringe (without piston) was pricked into a septum, respectively. This
way, by choice of the cannula, a leak of pre-defined size could be
created.

[0151] FIG. 3 shows the course of an optical signal with a leakage due to
puncture of the tubing set by means of a 0.4×19 mm-cannula.

[0152] As can be taken from FIG. 3, the average value of the optical
signal related to or obtained from the conveying device 5 being
circulating or conveying and the shut-off device 7 being closed (area 21;
average value is at about 889 dimensional units) is, unlike during the
experiment without leakage (FIG. 2), higher than related to or obtained
from the conveying device 5 standing still (area 23; average value is at
about 881 dimensional units). The difference value was about 8
dimensional units. This may be the result of the very low blood flow
possible due to the leakage.

[0153] The measurement or dimensional units may be, e.g., counts which are
obtained as follows: The signal receiving device as used in the examples
of the figures as described herein is a light receptor which is designed
or embodied as a light-to-frequency-converter. The sensor used thus
outputs a frequency proportional to the light intensity received. For the
evaluation, e.g., the edges of the signal are counted for a certain time
unit; each edge is thereby classified as a count.

[0154] With a correspondingly determined threshold value, by comparing a
difference hereto, a leakage alarm may be issued.

[0155] FIG. 4 shows the course of an optical signal with a leakage created
by means of a 0.6×25 mm-cannula during a reflection measurement.

[0156] In FIG. 4, it is easily recognizable that the signal course related
to our obtained from a circulating conveying device 5 and a closed
shut-off device 7 is significantly higher than the signal course related
to or obtained from a stillstanding conveying device 5.

[0157] The higher signal difference of FIG. 4--as compared to the course
of FIG. 3--may be attributed to the larger leakage created by means of
the 0.6×25 mm-cannula in FIG. 4 as compared to the one created by
means of the 0.4×19 mm-cannula from FIG. 3 and the thus admitted
larger flow (despite the shut-off).

[0158] FIG. 5 shows the course of an optical signal with a leakage created
by a 0.6×25 mm-cannula during a transmittance measurement. Apart
from that, anything that was said regarding FIGS. 2 to 4 applies.